Equipment for the packaging of products in a modified and controlled atmosphere, with a stretchable and gas-tight film

ABSTRACT

A packaging machine which carries out the conventional packaging of products with a stretchable and gas-tight film is housed in a main chamber ( 1 ) which is seable and contains a modified and controlled atmosphere suitable for the conservation of the product to be packaged. The product enters and leaves the main chamber by passing through corresponding sealable airlock chambers ( 7, 8 ) provided with corresponding automatic doors ( 107, 207, 108, 208 ) and in any case designed to provide a seal with respect to the external environment and to the main chamber to which these chambers are attached. When the outer sides of the airlock chambers are opened, their inner sides are closed, so that the modified and controlled atmosphere cannot issue from the main chamber. Before the airlock chambers are connected to the main chamber, these chambers have their outer sides closed and a mechanism may be provided to evacuate the ambient atmosphere from them and, if necessary, fill them with the modified and controlled atmosphere.

The invention relates to machines for the packaging with stretchablefilm of products normally previously disposed in trays, and concernsimprovements to enable these machines to form packages containing amodified and controlled atmosphere, with the aim of better conservationof the packaged product. The term “modified and controlled atmosphere”,or more simply “modified atmosphere”, denotes at least any one of thefollowing conditions:

a) an atmosphere different from the external ambient atmosphere,consisting of one or more gases suitable for the conservation of thepackaged product and having the same pressure as the externalatmosphere;

b) an atmosphere different from the external ambient atmosphere,consisting of one or more gases suitable for the conservation of thepackaged product and having a pressure greater than the externalatmospheric pressure;

c) an atmosphere identical to the external ambient atmosphere but at amarkedly lower pressure, typical of the packaging called “vacuumpackaging”;

d) an atmosphere different from the external atmosphere, formed by oneor more gases suitable for the conservation of the packaged product andhaving a pressure markedly lower than the external pressure, typical ofthe packaging called “vacuum packaging”.

The packaging of the products with stretchable film is at presentgenerally carried out with a gas-permeable film. However, stretchablegas-tight films are available at present on the market.

This patent application tackles the technical problem of how to be ableto provide any machine for packaging products with stretchable film, forexample the machine described in U.S. Pat. No. 3,967,433 (Bonfiglioli),capable of producing packages containing a modified atmosphere, suitablefor the purposes of conserving the product.

To resolve this problem, according to the known art of the packaging ofproducts with gas-tight, heat-sealable, but not stretchable film, it isnecessary, at the moment of formation of the packaging around theproduct, before its closure, to evacuate with suitable means the airinside the package, and, if necessary, to introduce the modifiedatmosphere into the package which at the correct time is heat-sealed andclosed so that it is gas-tight. The machines using these known solutionsare slow and of complex construction and doubtful reliability, since itis extremely difficult to control precisely the phases of evacuation ofthe ambient air from the package and of any refilling of the saidpackage with the modified atmosphere.

In the known art, the modified atmosphere, when it consists of gasesother than those of the ambient atmosphere, is generally prepared inadvance from time to time according to the type of product to bepackaged and is stored in a container from which it is taken graduallyin the necessary quantity. When the machine has to package a type ofproduct different from that of the preceding cycle, it is necessary toreplace the storage container which supplies the modified atmosphere. Itis evident that this condition impedes the rapid adaptation of themachine to the packaging of different products.

Packaging machines using stretchable film have a high output per hour,and would therefore be adversely affected by the aforesaid knownsolutions. In order to be able to produce packages with stretchablegas-tight film, under a vacuum and/or containing a modified andcontrolled atmosphere for the conservation of the product, it has beennecessary to devise a new solution which would be easily applied, wouldhave high technological reliability, and, above all, would allow thepackaging machine to operate at a high speed. According to theinvention, the formation and closure of the package with stretchablefilm are carried out in a main chamber with means which maintain in it amodified atmosphere according to at least one of the aforesaid fourconditions a), b), c), d). It is evident that the packaging cycle issimplified, since it is not necessary to use the present means whichoperate selectively on individual packages and it is possible to use anordinary packaging machine with stretchable film. Each package isprovided internally with the atmosphere modified for the purposes of theconservation of the product, since the same package is formed and closedin an environment which is completely filled with the modifiedatmosphere. The product enters and leaves the said main chamber bypassing through corresponding entry and exit airlock chambers which areprovided with corresponding doors for sealing with respect to theexternal environment and which are connected to the said main chamber.When the outer sides of the entry and exit chambers are opened, theirinner sides are closed, in such a way that modified atmosphere does notissue from the main chamber. Before the inner doors which connect theentry and exit chambers to the main chamber are opened, the outer sidesof these chambers are closed, and means may be provided to “evacuate”the ambient atmosphere from them and if necessary to introduce themodified atmosphere into them.

In the equipment according to the invention, when the packaging of theproduct has to be carried out in a modified atmosphere, the main chamberis also made to be connected to a plurality of storage containers, eachcontaining the primary gases which participate in the formation of themodified atmosphere for the conservation of the product, and mixingmeans are provided to control the supply of the gas from the saidcontainers and may be programmed so that the atmosphere required fromtime to time for the conservation of the products to be packaged isformed and maintained in the packaging chamber and if necessary also inthe airlock chamber. This solution permits a simple and rapid adaptationof the machine to the packaging of different products which requirecontrolled atmospheres having different characteristics.

The closest prior art know to applicant is repersented by documentFR-A-1 343 586. According to this document, there is disclosed a methodand apparatus for filling and closure of metallic drums with liquidsubstances in a sterilized environment. Apart from the different scope,clearly the apparatus according to the said prior art document differsin a substantial manner from the equipment in accordance with thepresent invention, as it will appear evident from the followingdescription.

Further characteristics of the invention and the advantages derivedtherefrom will be more clearly evident from the following description ofa preferred embodiment of the invention, illustrated purely by way ofexample and without restriction in the figures on the attached sheets ofdrawings, in which:

FIGS. 1 and 2 show equipment for packaging with stretchable film,improved according to the invention and capable of producing packagescontaining modified atmosphere or “vacuum” packages of the usual type orthose with a residue of modified atmosphere;

FIG. 3 shows schematically a variant embodiment of the equipment shownin the preceding figures, with means of collection in the phases offeeding and discharge of the products;

FIG. 4 is a schematic plan view from above and in partial section of anairlock chamber of the multiple-use type, with which it is possible tooperate at a high speed and with almost continuous cycles;

FIG. 5 shows details of the solution shown in FIG. 4, in section alongthe lines V—V;

FIG. 6 is a side view in partial section of another airlock chamber ofthe multiple-use type;

FIG. 7 shows details of the solution shown in FIG. 6, viewed through thesection line VII—VII.

FIG. 1 shows how the products P, disposed for example in trays 22, arefed cyclically by a conveyor 24 into an entry airlock chamber 7, whichis sealable and is for example of the tunnel type, having at itsopposite ends sealing doors 107, 207, of the guillotine type forexample, with corresponding operating means 9, 11. A conveyor 25 runslongitudinally in the chamber 7 and on the opening of the door 107receives the product from the said conveyor 24 and on the opening of theother door 207 transfers the said product to a sealable main chamber 1,to which the said chamber 7 is attached and which contains the variousand/or main components of an ordinary packaging machine usingstretchable film, for example one of the type cited in the introductionto the present disclosure. In the chamber 1, the product to be packagedis, for example, picked up by a comb conveyor, with belts 26, betweenwhich is disposed an elevator 27 which when commanded raises the productto the packaging station, as indicated in broken lines. The packagingfilm, which is gas-tight and stretchable, is unwound from a reel 28 andrun around means 29, 30, then passes through a dispenser 31 and is heldat its end by a gripper 32 which on command can be driven with ahorizontal movement of approach to and withdrawal from the saiddispenser 31, to spread in the packaging station a portion of film 23against which the product to be packaged is subsequently raised andpushed. With suitably combined movements of the gripper 32 with thepusher 34 and lateral grippers and folders 33, the product is moved tothe static folder 35, while the four flaps of the portion of film 23controlled by these means are folded under the product and areoverlapped on each other. At the correct time, the elevator 27 returnsto the low position and the portion of film 23 which wraps the productis cut by suitable means indicated schematically by the arrow 36. Thenumber 37 indicates the presser which holds the product correctly duringthe packaging phase. While the gripper 32 is lowered under the folder 35and grips the new leading edge of the film held by the dispenser 31, thepackaged product moves on to the conveyor 38 which heat-seals theoverlapping flaps of the packaging film 23.

The wall of the chamber 1 which is located after the heat-sealingconveyor 38 is attached to a sealable airlock chamber 8, designed forthe discharge of the packaged product and having on its opposite sidessealing doors 108, 208, of the flap type for example, with correspondingactuators 10, 12. A conveyor 39 runs longitudinally in this chamber 8and on the opening of the door 208 receives the product from the saidconveyor 38 and on the opening of the door 108 discharges it from theairlock chamber in question.

According to the invention, the main chamber 1 is connected to at leastone conduit 2 leading from a battery of containers 4 for the storage ofthe various gases necessary for the formation in the said chamber of thecontrolled atmosphere which is necessary from time to time for thepackaging of the products, the exit of the gases from these containersbeing controlled by intercepting and mixing means 3 which in turn arecontrolled by a central processor 5 with a screen and programmingkeyboard. The processor 5, by means of a sensor 6, detects thecomposition and/or quantity of the atmosphere in the chamber 1 and isdesigned in such a way that, by the preceding means 2, 3, 4, it canmaintain a modified atmosphere within predetermined and programmedparameters in the chamber 1.

The actuators 9, 10, 11 and 12 which control the opening and closing ofthe doors 107, 207 and 108, 208 of the airlock chambers 7, 8 areconnected to a supply interface 100 which is also controlled by theaforesaid central processor 5.

According to a preferred embodiment of the invention, the chambers 7 and8 are connected at 113 and 114 to corresponding suction means 13, 14,controlled through the appropriate interface 101 by the processor 5,and, in opposition to these means, conduits 15 and 16, connected forexample to part of the group 3, are joined to the said chambers for theintroduction of a controlled atmosphere on command.

The equipment designed in this way operates as follows. The processor 5is used to determine the characteristics of the modified atmospherewhich is to be created and maintained in the main chamber 1, and thesaid processor, by means of the monitoring provided by the sensor 6,automatically keeps these characteristics constant. At the start of eachoperation of the equipment, the outer doors 107 and 108 are closed,while at least one or both of the inner doors 207, 208 are opened sothat the main chamber communicates with one or both of the airlockchambers and in these conditions the pumps 13 and 14 are operated toextract the ambient air from the chambers, after which the said pumpsare stopped, the inner doors 207, 208 are closed and the processor 5operates the means 3, 4 to introduce into the main chamber theconservation gas or gases in the necessary quantity and at the necessarypressure. The start of an operating cycle requires the opening of theouter door 107 and the operation of the conveyors 24 and 25 for theintroduction of a product into the entry chamber 7, after which the saidconveyors are stopped, the said door is closed and means 13 come intooperation for the evacuation of the ambient atmosphere contained in thechamber 7 and the conduit 15 is then operated to introduce some of thecontrolled atmosphere into the said chamber 7. At this point, the door207 is opened, and the conveyors 25 and 26 are operated to transfer theproduct from the entry chamber 7 to the main chamber 1, above theelevator 27, after which the said conveyors are stopped and the door 207is re-closed to isolate the chamber 7 from the chamber 1. While the nextproduct is fed into the chamber 7, the product which was previouslyintroduced into the chamber 1, on to the elevator 27, is raised by thelatter, forced against the portion of film 23 spread in the packagingstation and is wrapped with this film by the combined action of thegroup of lateral grippers and folders 33, the frontal folders 32-35 andthe pusher 34, while the cutting means 36 come into operation at thecorrect time to separate the packaging film from the dispenser 31. Partof the modified atmosphere which uniformly occupies the main chamber 1remains trapped in the packaging 23 which wraps the product, and thiscondition is made stable and permanent when the packaged product passeson to the heat-sealing conveyor 38 which seals the overlapping flaps ofthe package.

While the aforesaid phase of packaging is being executed in the mainchamber 1, in the exit chamber 8 the means 14 for evacuating the ambientatmosphere are operated, and the modified atmosphere is introduced intothis chamber through the conduit 16. When the packaging of the productis completed in the chamber 1, the door 208 of the chamber 8 is openedand after the passage of the product this door is re-closedautomatically. Subsequently the door 108 is opened and the conveyors 38and 29 are operated to discharge the packaged product from the chamber8, after which the whole cycle described above is repeated.

Suitable means may be provided by which the modified atmosphere whichoccupies the chambers 7 and 8 is alternatively recovered instead ofbeing dispersed into the atmosphere. To simplify the machine, theconduits 15, 16 may also be eliminated, since the introduction of thecontrolled atmosphere into the airlock chambers 7 and 8 may be carriedout alternatively by the main chamber 1 when, on completion of theevacuation of the ambient atmosphere from the said chambers 7 and 8,these are put into communication with the main chamber by the opening ofthe inner doors 207, 208.

The airlock chambers 7, 8 preferably have the smallest possible volume,in order to simplify the operations of evacuation of the ambientatmosphere from them and subsequent saturation with the modifiedatmosphere. However, it is to be understood that the entry and exitchambers may alternatively have volumes such that a phase ofaccumulation or collection of the products is provided, in order toensure a continuous and rapid operation of the packaging machine whichoperates in the same chamber 1 and to limit the packaging frequency ofthe airlock chambers 7-8. FIG. 3 shows such a variant, according towhich the conveyors 25 and 39 of the airlock chambers 7, 8 and theconveyors 26 and 38, which respectively supply the elevator 27 and carryout the heat sealing of the package 23, have a length such that morethan one product can be supported.

The simple way in which the problem of the packaging of the products ina modified atmosphere is resolved is evident, since it is therebyunnecessary to create and/or introduce the conservation atmosphere intothe individual packages. It is also evident that, by the simpleprogramming of the processor 5, it is possible to prepare the equipmentrapidly for the packaging in a modified atmosphere of any type ofproduct which requires any suitable mixture of the principal gases fromthe storage containers 4.

The equipment illustrated in the variant shown in FIG. 2 relates to whatis called “vacuum” packaging of the products. This equipment differsfrom the equipment shown in FIG. 1 in the absence of the storagecontainers 4 of the gases to form the controlled conservation atmosphereand of the corresponding programmable mixer 3, as well as in the absenceof the conduits 2, 15, 16 for introduction of the modified atmosphereinto the main chamber 1 and into the airlock chambers 7, 8. In thiscase, the airlock chambers 7, 8 are acted on only by the suction means13, 14 which can produce the vacuum in these chambers before they areconnected to the main chamber 1 which is also connected to a suctionpump 40 controlled by the processor 5 through the interface 41, tomaintain a correct vacuum level in this chamber. The numbers 17 and 18indicate solenoid valves which on command connect the chambers 7 and 8to the ambient atmosphere before the opening of the outer doors 107,108, in such a way that this opening is facilitated. According to avariant embodiment of the solution shown in FIG. 2, the pumps 13 and 14may be eliminated when the volume of the airlock chambers 7, 8 islimited, since the small variations of pressure created in theconnection of such chambers to the main chamber can easily becompensated by the main pump 40.

By combining the solutions described and illustrated in FIGS. 1 and 2,in a way which can be easily understood and applied by those skilled inthe art, it is possible to produce equipment capable of producingpackages in a vacuum which contain within them residues, not of theambient atmosphere, but of a controlled atmosphere suitable for thebetter conservation of the packaged product. In this case, at least themain chamber 1 and if necessary also the airlock chambers 7, 8 will beconnected to the corresponding conduits 2, 15, 16 for supplying theconservation gas or gases from the means 3 and 4 mentioned previouslywith reference to FIG. 1. The considerations mentioned with reference toFIG. 3 are also applicable to the variant shown in FIG. 2.

To provide faster operation of the machine, each of the airlock chambers7, 8 may be formed from a plurality of chambers disposed in a closedring, one after another, and arranged in such a way that while a firstchamber is connected to the exterior to receive a product, at least onesecond and subsequent chamber containing the product is in the processof modification of the internal atmosphere, and a third chamber, withthe internal atmosphere already modified, is in communication with themain chamber 1. At least one fourth airlock chamber is closed anddisposed after the third of the said chambers, between this and thefirst chamber, so that, when the said airlock chambers are moved by onestep and change their relative positions, a product is loaded into anddischarged from the main chamber and this chamber is never connected tothe exterior.

A first embodiment of this concept of a solution is shown in FIGS. 4 and5 and relates to the airlock chambers 7 which supply the product to themain chamber 1. The airlock chambers 7 are formed by the division intoradial segments of a cylindrical hollow structure 42, in the form of aturret, which, at the command and by the action of suitable means whichare not illustrated, rotates by steps about its vertical axis, forexample in the clockwise direction indicated by the arrow 43. Eachairlock chamber comprises its own bottom and top walls 307 and its ownside walls 407, is open towards the outside and carries at a shortdistance from its base a small horizontal conveyor 25 which is alignedinitially with the external conveyor 24 to receive a product to bepackaged, and is then aligned with the conveyor 26 of the chamber 1, totransfer the product to the elevator of the packaging machine. Theconveyors 25 may be free-running and may be made to rotate by theconveyor which they contact, for example by means of a coupling deviceof the oscillating type formed by friction or gear wheels 44 which arebrought by an actuator (not illustrated) from the rest positionindicated by the solid lines in FIG. 5 to that indicated by the brokenlines, and vice versa. During the clockwise stepping rotation of theturret 42, the edges of the apertures of the airlock chambers 7, withthe corresponding seals 45, interact with a fixed wall 46 which closesthe said chambers and to which are attached the connections 113 and 15which create the vacuum in the airlock chambers and introduce themodified atmosphere if necessary. In the subsequent movement away fromthe main chamber 1, the airlock chambers 7 are closed at least initiallyby a fixed wall 47, which prevents the connection of the chamber 1 tothe exterior through the said chambers 7. It is evident that themodified atmosphere which remains in the airlock chambers which leavethe chamber 1 can be usefully recovered by suitable means and introducedinto the left-hand chambers which move towards the main chamber. Thesolution shown in FIGS. 4 and 5 can also be used for the construction ofthe airlock chambers 8 which discharge the packaged product from themain chamber 1.

FIGS. 6 and 7 show another embodiment alternative to that shown in FIGS.4 and 5, according to which the airlock chambers 7 are formed by anapron conveyor or toothed belt conveyor 48, running around a pair oftoothed pulleys 49, 50 with horizontal and parallel axes, one of whichis driven by a geared motor 51 which by means of the positivetransmission 52 drives a further apron or belt conveyor 53 runningparallel to and under the said conveyor 48. The conveyor 48 has aplurality of identical and equally spaced transverse plates 54 which inthe lower path of this conveyor touch the conveyor 53 and thus form theairlock chambers 7 which are closed laterally by fixed walls 55, 56, toone of which are attached the conduits 113, 15 which create the vacuumand introduce the modified atmosphere if necessary. Opposite theconveyor 53 there is provided a fixed casing 57 with which the plates 54interact to prevent the connection of the main chamber 1 to the exteriorat least in the first section of the path of the airlock chambers awayfrom the said main chamber. This solution may also be used for theconstruction of the airlock chambers 8.

The chambers 1, 7 and 8 of the equipment are made in such a way as toallow simple and rapid access to the parts disposed in them, for examplefor the replacement of the reel of film in the main chamber and/or forany maintenance requirement, and are preferably made wholly or partiallyfrom transparent material which reveals the operation of the internalcomponents.

What is claimed is:
 1. An apparatus for packaging products with astretchable gas-tight film, comprising: a wrapping machine which forms apackage for the product which is sealed with respect to an ambientatmosphere, said wrapping machine including a) a reel of stretchablegas-tight film, b) an unwinding means for cyclically unwinding a portionof the film from the reel, c) a wrapping means for wrapping the productwith the portion of film and for forming overlapping flaps of the film,and d) a sealing means for sealing the overlapping flaps of the film toform the sealed package; a sealable main chamber in which said wrappingmachine is completely contained; an atmosphere means for creating andmaintaining said chamber with a modified atmosphere havingcharacteristics suitable for the conservation of the products packagedin said wrapping machine and modified with respect to the ambientatmosphere; a sealable entry airlock chamber connecting said mainchamber with the ambient atmosphere, said entry airlock chamberincluding a) an entry passage means for passing the products to bepackaged into said entry airlock chamber from the ambient atmosphere, b)entry sealing doors by which an interior of said entry airlock chamberis connected to the ambient atmosphere and to the main chamber; asealable exit airlock chamber connecting said main chamber with theambient atmosphere, said exit airlock chamber including a) an exitpassage means for passing the packaged products into the ambientatmosphere from said exit airlock chamber, b) exit sealing doors bywhich an interior of said exit airlock chamber is connected to theambient atmosphere and to the main chamber; a control means forcontrolling said sealing doors such that a) in a first action of saidcontrol means, said entry airlock chamber is closed to the main chamberand opened to the ambient atmosphere, b) in a second action of saidcontrol means, said entry airlock chamber is closed to the ambientatmosphere and opened to the main chamber, c) in a third action of saidcontrol means, said exit airlock chamber is closed to the ambientatmosphere and opened to the main chamber, and d) in a fourth action ofsaid control means, said exit airlock chamber is closed to the mainchamber and opened to the ambient atmosphere; an introducing means forintroducing a product to be packaged into said entry airlock chamberafter said first action of said control means; an entry transferringmeans for transferring the product from the entry airlock chamber to themain chamber after said second action of said control means whereby saidwrapping machine in said main chamber then forms the package with aportion of the modified atmosphere trapped in the wrapped product; anexit transferring means for transferring the wrapped product into saidexit airlock chamber from said main chamber after said third action ofsaid control means; and a discharging means for discharging the wrappedproduct from said exit airlock chamber after said fourth action of saidcontrol means; wherein said entry airlock chamber further comprises a) atransfer conveyor mounted on pulleys with horizontal axes such that saidtransfer conveyor is divided into a lower straight run and an upperstraight run, b) a series of plates fixed to said transfer conveyor atequal intervals to divide the interior of said entry airlock chamberinto respective chamber portions, c) respective side pieces provided onrespective lateral sides of said transfer conveyor such that respectivelateral edges of said plates interact respectively therewith to form aseal; d) an underlying horizontal belt conveyor on which the productsare supported and which is i) positioned underneath the lower straightrun of said transfer conveyor, ii) connected mechanically to saidtransfer conveyor, and iii) spaced from the lower straight run of saidtransfer conveyor so that horizontal edges of said plates interact andform a seal therewith, e) a fixed casing integral with said side pieceswhich is located above said upper straight run of said transfer conveyorand which is spaced from the upper straight run of said transferconveyor so that the horizontal edges of said plates interact and form aseal therewith, and f) a second atmosphere means for creating themodified atmosphere in each said chamber portion as each said chamberportion is located along said horizontal belt conveyor and is isolatedfrom the ambient atmosphere; and such that in a cyclic manner thechamber portions change positions when advanced through an intervalequal to the distance between said plates so as to constantly keep saidmain chamber isolated from the ambient atmosphere and so that, a) whilea first chamber portion is connected to the ambient atmosphere toreceive the product to be packaged, b) at least a second and subsequentchamber portion containing the product to be packaged is isolated fromthe ambient atmosphere and connected to said second atmosphere means, c)while a third and subsequent chamber portion containing the modifiedatmosphere and product is in communication with said main chamber forthe introduction into said main chamber of the product to be packaged,and d) at least a fourth chamber portion is provided which is sealedfrom the ambient atmosphere and from said main chamber and which islocated after the third chamber portion and between the third chamberportion and the first chamber portion.
 2. An apparatus for packagingproducts with a stretchable gas-tight film, comprising: a wrappingmachine which forms a package for the product which is scaled withrespect to an ambient atmosphere, said wrapping machine including a) areel of stretchable gas-tight film, b) an unwinding means for cyclicallyunwinding a portion of the film from the reel and for feeding theportion of the film to a wrapping station, c) an elevator which liftsthe product against the portion of the film at the wrapping station, d)a wrapping means at the wrapping station for folding the portion of thefilm about the product so that the flaps of the portion of the film areextended under tension onto a bottom of the product, and e) a sealingmeans for sealing the overlapping flaps of the film to form the sealedpackage; a sealable main chamber in which said wrapping machine iscompletely contained; an atmosphere means for creating and maintainingsaid chamber with a modified atmosphere having characteristics suitablefor the conservation of the products packaged in said wrapping machineand modified with respect to the ambient atmosphere; a sealable entryairlock chamber connecting said main chamber with the ambientatmosphere, said entry airlock chamber including a) an entry passagemeans for passing the products to be packaged into said entry airlockchamber from the ambient atmosphere, b) respective exterior and interiorentry sealing doors by which an interior of said entry airlock chamberis alternatingly connected to and sealed from the ambient atmosphere andthe main chamber respectively, said exterior and interior entry sealingdoors i) being respectively fixed relative to an entrance and exit ofsaid entry airlock chamber and ii) being formed as a respective entryguillotine member having a respective entry actuator providing arectilinear reciprocating motion for moving each respective said entryguillotine member; a sealable exit airlock chamber connecting said mainchamber with the ambient atmosphere, said exit airlock chamber includinga) an exit passage means for passing the packaged products into theambient atmosphere from said exit airlock chamber, b) respectiveexterior and interior exit sealing doors by which an interior of saidexit airlock chamber is alternatingly connected to and sealed from theambient atmosphere and the main chamber respectively, said exterior andinterior exit sealing doors i) being respectively fixed relative to anexit and entrance of said exit airlock chamber and ii) being formed as arespective exit guillotine member having a respective exit actuatorproviding a rectilinear reciprocating motion for moving each respectivesaid exit guillotine member; a control means for controlling saidsealing doors such that a) in a first action of said control means, saidentry airlock chamber is closed to the main chamber and opened to theambient atmosphere, b) in a second action of said control means, saidentry airlock chamber is closed to the ambient atmosphere and opened tothe main chamber, c) in a third action of said control means, said exitairlock chamber is closed to the ambient atmosphere and opened to themain chamber, and d) in a fourth action of said control means, said exitairlock chamber is closed to the main chamber and opened to the ambientatmosphere; an introducing means for introducing a product to bepackaged into said entry airlock chamber after said first action of saidcontrol means; an entry transferring means for transferring the productfrom the entry airlock chamber to the main chamber after said secondaction of said control means whereby said wrapping machine in said mainchamber then forms the package with a portion of the modified atmospheretrapped in the wrapped product; an exit transferring means fortransferring the wrapped product into said exit airlock chamber fromsaid main chamber after said third action of said control means; and adischarging means for discharging the wrapped product from said exitairlock chamber after said fourth action of said control means.